This invention relates generally to a method of producing envelope to RF cycle differences (ECD) in pulse transmitters, for example Loran, and more particularly to a method of varying the relationship of the RF cycles inside the resulting pulse envelope with reference to the envelope start.
The term "pulse envelope" as employed herein in the specification and claims is that pulse shape obtained by connecting the peaks of the RF cycles with an imaginary line.
In co-pending application, Ser. No. 515,788, filed Oct. 17, 1974 entitled "Feedback System for Pulse Transmitters", now U.S. Pat. No. 3,955,144, issued May 4, 1976 and assigned to the assignee of the present invention, it was shown that a correctly predistorted driving waveform could be obtained from certain unique outputs produced by a specially designed filter network driven by a simple impulse.
In many pulse systems, particularly Loran, the capability of being able to move the RF cycles of a waveform inside the envelope of the RF cycles without moving the envelope itself is required. In Loran, this relationship between the RF cycles of the waveform and the envelope of the RF cycles is called ECD; i.e. the envelope to cycle difference, and it is desired to be able to phase shift the RF cycles by 180.degree. in either a positive or negative direction, while at the same time maintaining the envelope stationary.